birdawesome

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@birdawesome , so you’re changing the ‘63 RI bridge rectifier to the older 6G15/mojo/StewMac rectifier?

I’m curious to see when yours is done what the voltages look like and if the PT feels warmer than expected while its running
It wasn’t really a conscious decision to do so, rather than just following their build. If I have issues with the power maybe I’ll change it over, but I run my rig off a Furman power conditioner, so I’m hoping that cleans it up enough to make the difference negligible. I’ll report back!
 

SerpentRuss

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Just a little update:

Here's where I'm currently at. Sorry the lighting isn't great, it got dark and my lamps aren't very adequate. Have it all back together expect for V1 and V2, which I wanted to start clean using new tube sockets with. My wiring is cleaner this time around, and I triple checked all of my connections...if I've missed something this time my optometrist is up for a visit. Hoping once I get these sockets installed and wired it'll be smooth reverb-ing! View attachment 1019716 View attachment 1019717 View attachment 1019718
Your work looks good.

I would not have opted for the original, three series diodes, power supply. You could put in a well-filtered, full wave supply and ditch the choke. This reverb unit draws almost no HT current, which is why Fender was able to get by with that PS, which is really a POS-PS, in my book.

Also, you may want to consider elevating your heater supply because of the architecture of output section with the cathode of the one stage of the 7025 at 130 volts. You could also engineer in a permanent ground-lift circuit as many retrofitted to these units to quiet them down.
 
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birdawesome

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Your work looks good.

I would not have opted for the original, three series diodes, power supply. You could put in a well-filtered, full wave supply and ditch the choke. This reverb unit draws almost no HT current, which is why Fender was able to get by with that PS, which is really a POS-PS, in my book.

Also, you may want to consider elevating your heater supply because of the architecture of output section with the cathode of the one stage of the 7025 at 130 volts. You could also engineer in a permanent ground-lift circuit as many retrofitted to these units to quiet them down.
If I end up running into issues with it then that’s what I’ll do. At the moment I just want to get the unit working again before I start looking to mod the circuit.

And yes, I’ll elevate my heater supply. I realized after my photos that I would probably get some issues with them the way they are.

A ground lift alone would be a great addition! A permanent ground lift would be great too, but if I don’t find I get any hum then I may not need to. Before I tore it apart, this reissue didn’t have any issues whatsoever with noise or anything of the like. Even when I got my unit powered up before, despite the reverb not working, my signal was nice and clean except for when the foot switch was attached.

I’ll keep y’all updated though and let you know what direction I go in!
 

SerpentRuss

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If I end up running into issues with it then that’s what I’ll do. At the moment I just want to get the unit working again before I start looking to mod the circuit.

And yes, I’ll elevate my heater supply. I realized after my photos that I would probably get some issues with them the way they are.

A ground lift alone would be a great addition! A permanent ground lift would be great too, but if I don’t find I get any hum then I may not need to. Before I tore it apart, this reissue didn’t have any issues whatsoever with noise or anything of the like. Even when I got my unit powered up before, despite the reverb not working, my signal was nice and clean except for when the foot switch was attached.

I’ll keep y’all updated though and let you know what direction I go in!
I think the reissue had a permanent ground lift. You may find your rewire noisier.
 

birdawesome

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Outter jack sleeve was contacting the chassis
I’m a bit confused by that though...shouldn’t it be doing that? The sleeve should be grounding so noise picked up by the shielding gets sent to ground. Unless you’re getting a ground loop somewhere, why would it need to be isolated from the chassis?
 

birdawesome

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Okay guys, I'm about at my whit's end. I completely rebuilt the unit with all new capacitors and tube sockets, and I'm still running into the same issue. Albeit, this time my voltages on my filter caps are looking healthier (360V) and my dry signal coming through the unit is nice and loud and clear, as well as the tank crash sounding nice and clear too. The unit is also pretty clean in regard to any buzz/hum.

However, the unit is still seemingly not sending my guitar signal to the reverb pan. I've switched pans, cables, RCA jacks, and tubes, and none of it has made a difference.

I've taken voltage readings across all my pins, this time without tubes. I'll post one with tubes in tomorrow, but for tonight I'm frustrated and very tired. All voltages are DC unless otherwise specified.

My V2 is still nowhere near what it should be, with very low voltages across 1 and 6. 2, 3, 7, and 8 should be 0V I think. V1 is looking alright except for 1 and 6, which I think should be 120V.

Any help y'all can give me to push this across the finish line would be unbelievably appreciated. Also, a couple pics of the new build, which is quite a bit cleaner if I do say so myself.
No Tubes Voltages.png
 

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tubeswell

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You've probably got a signal wire missing. Use your R-meter to check DC-continuity for all eyelets that are supposed to have connections to other eyelets (including behind the board etc)
 

Snfoilhat

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If the builds came out with the same fault, I would guess that the builder is misinterpreting a detail in the layout. I would print the schematic on paper and walk through every connection around V2, checking them off. In the vintage Fender style of schematic, actual connections are shown with a dot. You can pick each dot and then confirm all 2, 3, or 4 wires or components are electrically connected there. Just a trick to give you fresh eyes when your memory insists you followed the layout correctly
 

sudogeek

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Lots of problems.

Let’s start with V1, the 12ax7: It depends on how you are wiring it. Is A (pins 1-3) the dry side and B (pins 6-8) the wet side? Functionally, it doesn't matter but you need to be sure to wire each side appropriately. To which pin is output from the reverb return jack wired? That is the wet side.

I'm guessing you wired pins 1-3 as the dry side as the voltage on pin 1 is high. The spec voltage on pin 1 is 250VDC but it will be higher with the tubes out. However, pin 7 should have >100V on it.

The wet side (pin 6-8?) should show about >150VDC on pin 6 and no volts on pin 7 with the tubes out. As reported, this is mis-wired. As written, you should not have any signal from the pan. Did you reverse the values?

On V2 , the 12at7: pin 1 and pin 6 should both have 120-150VDC+. This is also mis-wired or there is an error in the power supply wiring.

You need to carefully review the wiring on these two tubes. Take measurements with the tubes in and the unit on.

Edit: Here are some voltages from my last reverb unit build several years ago. I do not have full voltages with the tubes out. Further, this build used a bridge rectifier.

Tubes out:
Input 119V AC
B 329 V
B+1 329V
B+2 328V

All tubes in:
B 324V B+1 290V B+2 246V
6K6GT: pin 3 284V pin 4 292V
12AT7: pin 1 120V pin 3 1.7V pin 6 128V pin 8 1.7V
12AX7: pin 1 157V pin 3 1.3V pin 6 246V pin 7 113V pin 8 125V
Note the voltages on pins 6-8 - this is the dry side. Pin 7 is wired (through a cap) to the input jack.

[As an aside and OT: I don’t like to wire a build with all one color wire. It can be a bit more difficult to pick up mistakes. There is no published standard, though. I generally do DC grounds in black, heaters in green (I use a light and a dark green to keep the two sides separate) or green and white, the DC power in red, and signal yellow. I don’t always keep exactly to this scheme, depends on what I have on hand. I just find it easier and it really helps when you’re looking at pictures.]
 
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birdawesome

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I GOT IT!

Turns out the root of all the issues was due to a mistake reading the wiring diagram on my part. To my credit though, the wiring diagram is very deceptive, which is why I made the same mistake twice. I had to trace back through the schematic as suggested, until I got to a path that wasn't adding up, which is when I discovered I had essentially bridged pin 6 of the V1 and V2 together, with only a resistor in-between, when they were supposed to be both connected by jumpers to the 2.2M/100K eyelet powered by the filter caps. I attached some photos so y'all can see exactly what I'm talking about. Once I corrected that, my unit worked great!

Thank you so much to all of you that helped me along the way. This was my first build, so it looks like it paid off in the end by learning a lot along the way, which is exactly why I wanted to do it in the first place.


Now the only thing to troubleshoot/fix is the horrible noise I get from my foot switch acting as an antenna...very whiney and sizzly. With Tubes_After Fix.png
 

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sudogeek

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Pro tip from the 60s: Better shielded cable connecting the foot switch to the unit is key. In the 6G15 design, the actual reverb signal traverses to the footswitch and back. Basic Fender footswitches with the cheap cable don’t work so well. But, take an quality instrument cable and solder the footswitch on one end and the RCA plug on the other. That works much better.
 

birdawesome

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Pro tip from the 60s: Better shielded cable connecting the foot switch to the unit is key. In the 6G15 design, the actual reverb signal traverses to the footswitch and back. Basic Fender footswitches with the cheap cable don’t work so well. But, take an quality instrument cable and solder the footswitch on one end and the RCA plug on the other. That works much better.
Ah that makes sense. I didn't realize the signal actually travelled through the foot switch itself. Makes perfect sense that the cable would be putting all that noise in the signal then without a proper shield. I'm using a repro pedal from Sheehan


And there's no shielding, just two conductors. Plugged in the foot switch that came with my CS Princeton and it was dead silent. I'll either have to use this other foot switch or replace the cable in the other one to something shielded. Thank you!
 

Freeman Keller

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Glad you got it, I won't bother posting my voltages. However that connection is basically the one that I failed to do and had to install a jumper to tie those points together. After that my voltages all became reasonable.

Curious how you like the sound.
 

birdawesome

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Glad you got it, I won't bother posting my voltages. However that connection is basically the one that I failed to do and had to install a jumper to tie those points together. After that my voltages all became reasonable.

Curious how you like the sound.
Yes, once I figured out the issue I was kicking myself for not looking into your solution further! I was just confused because I was still under the impression the connection wasn't supposed to exist, considering my misreading the wiring diagram. But, looks like we essentially had the same problem.

As far as the sound goes, it sounds great. Granted, I'm using a Mod tank and not the stock Accutronics tank, as well as NOS tubes (6K6 instead of 6V6 also). I may end up swapping back to the 6V6 though, and see if I get a better S/N ratio, and not need to have the Dwell up as high, which brings in more noise. However, I don't know if the noise is being introduced pre or post 6v6/6K6, so the higher gain tube may just end up bringing the noise even more.

Regardless, I run my unit on a pretty low Dwell and Mix setting, so noise isn't really an issue anyways. But, it's always nice to have more clean headroom!
 




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